Phoenix police released security camera footage of several men they believe were involved in the shooting death of a woman who tried to stop them from robbing a man in 2017.

Police said 45-year-old Crystal Brown was killed Aug. 31 near 15th Avenue and Buchanan Street during a confrontation with a group of men, at least one of whom was armed.

Witnesses reported at the time that a group of three men approached another man and held him at gunpoint while they were attempting to take his bike, police said.

Brown and another person intervened in the attempted robbery, which caused the men to turn their attention to them, police said.

Phoenix police Sgt. Mercedes Fortune said Brown didn't know the men and the confrontation began as a verbal exchange before escalating. One of the men then shot Brown, who was taken to a hospital, where she was pronounced dead.

The three men fled the scene and police were unable to locate any suspects.

Investigators are now asking for the public's help in identifying the three men, who were caught on security camera footage shortly after the shooting. All of the men involved are believed to be in their late teens or early 20s.

Anyone with any information is asked to call the Phoenix Police Department or Silent Witness at 480-WITNESS (480-TESTIGO).